Process for catalytically hydrogenating organic substances



Dec. 14, 1948. H. M. GUINOT 2,456,187

PROCESS FOR CATALYTICALLY HYDROGENATING ORGANIC SUBSTANCES Filed June 15, 1945 Patented Dec. 14,. 1948 PROCESS FOR CATALYTICALLY HYDRO- GENATING ORGANIC SUBSTANCES Henri Martin Guinot, Versailles, France, assignor to Les Usines De Melle (Soclete Anonyme), Saint-Lger-les-Melle, France, a company of France Application June 15, 1945, Serial No. 599,607 In France September 5, 1941 "Section 1, Public Law 690, August 8, 1946 Patent expires September 5, 1961 2 Claims. (Cl. 260-690) Since the celebrated works of Sabatier in respect of hydrogenation of organic substances in gaseous phase in the presence of reduced metals acting as catalysts, various industrial applications of his methods have been made. As a matter of fact, it is almost exclusively nickel catalysts which have been used in actual practice by reason of their general qualities, although the high temperature to which the catalysis oven should be raised to secure reduction of oxide is a serious hinderance to the development of like processes.

As to copper, the oxide of which is readily reduced, its employment has sometimes been proposed (for instance in French Patent No. 639,756 filed January 31,1927) but remains an exception, the said catalyst being considered rather as one suitable to promote dehydrogenation particularly of alcohols while its potency in respect of pro moting hydrogenations is generally regarded as of second-rate.

In contradistinction with prevailing opinion, I have now found that copper catalysts are capable of promoting a larger number of hydrogenations with an activity equivalent to that of the best nickel catalysts, provided said copper catalysts are suitably prepared.

It is known that in conventional reduction of precipitated copper oxide laid in a tube through which a stream of hydrogen is passed, heat evolution can be so large that the mass is sometimes raised to red heat at successive places, and portions of molten copper may be found locally thus showing a temperature elevation above 1,i C.

I have ascertained that any precautions taken to avoid such phenomena, particularly the use of a stream of hydrogen admixed with inert gas, fail efilciently to prevent the local elevations of temperature. In spite of said precautions, it is not unfrequent to detect by means oi thermometers having a small inertia, temperatures abruptly rising above 500 0., while thermometers positioned downstream with respect to the direction of hydrogen blow, i. e. nearer to theoutlet of the tube, indicate no perturbation and remain at the predetermined temperature, for instance It is obvious that at so high temperatures, copper becomes strongly annealed without one suspects it unless abrupt rising of a thermometer positioned in the zone where reduction starts and whenceit proceeds to next zones has been obsei ved. Hence a momentous decrease of catalytic action occurs.

It is an object of my invention to produce cop- ,1

\ per catalysts and to provide a method of, usin \the same, whereby any'undesired rise or temperature during reduction of oxide is absolutely precluded, and catalysts having a remarkable potency and very long life are obtained, said catalysts being suitable to be substituted with advantage for nickel catalysts in a large number of hydrogenations.

According to this invention, I use heat evolved both during reduction and hydrogenation proper to evaporate water around tubes in which the catalyst is positioned, by adjusting pressure in the inter-tube space so as to hold water temperature at the desired value.

As the temperature at which either copper oxide reduction or hydrogenation of materials to be treated can be performed is rather low, it is easy for starting either reaction to bring water around the tubes to the desired temperature by simple heating for instance with live steam at a suitable pressure, which may vary according as the case may be from 1 kg to 10 kgs (absolute pressure) per square centimeter.

To sum up. in order to start reduction of copper oxide catalyst, sufllce it to heat the vwhole apparatus by supplying itwith live steam, while during the other operations (oxide reduction or hydrogenation of material) the apparatus will operate as a steam producer; the steam may be employed for any purpose. I

Any suitable apparatus can be used for carrying out this invention into practice. By way of non-iimitative illustration I have shown in the appended drawing an apparatus found to be suitable for carrying my process into practice and I shall now proceed with'its description.

In a bundle of tubes A, A1, A2 etc., I place lozenges or tablets of catalysts made of copper oxide precipitated on an inert vehicle or carrier of any kind such as silica, kieselguhr, pumice, powdered or fibrous asbestos, with or without promoting agents. The tubes are held by two perforated plates B, B1 in a casing C of any shape, the whole apparatus resembling a conventional evaporator, capable of resisting pressure.

Water is placed outwardly with respect to the tubes, nearly completely filling the inter-tube space.

The catalyst containing tubes are connected other hand with a tubular vaporizer E and a tan F. The fan is provided to force gases first into vaporizer E wherein liquid to be hydrogenated is further vaporized, thence through catalysis tubes A, A1, A2 etc. and finally into condenser "Rafter on the one hand with a condenser D and on the which is a vessel G for collecting condensed liquids.

Gases and non-condensed vapours are again taken up by tan F via pipe and so on. A trap valve H is provided automatically to allow for introduction oi hydrogen under predetermined pressure irom gas tank I in proportion to its being used in catalysis oven (1. e. in the bundle of tubes A, Al etc).

.inter-tube space to keep a constant water level therein.

The operation is as ioliowsi.

Tubes A. A1, A: etc, are first charged with precipitated copper oxide or with copper oxide produced by calcination ata low temperature and the whole circuit is filled with nitrogen. Live steamat a pressure of 4 kgs. per sq. cm. is admitted past valve M controlling an apertured worm in the inter-tube space, bubbles through water in said space and heats it. A blow-oil cock (not shown) is provided to remove excess water from condensed steam.

As valve J, adjusted to maintain around tubes A, A1, A: etc. an absolute pressure of 4 kgs. per sq. cm. corresponding to a temperature of 140 0., begins to operate, heating is cut oil. and fan F is started, thereby further unii'ormising temperature at all points in said tubes. By opening a small blow-oil cock N positioned upstream with respect to fan F, a little nitrogen is expelled, being replaced by pure hudrogen from gas tank I owing to operation of trap valve H.

Reduction immediately takes place; it is the more rapid as the proportion oi hydrogen admitted into the cycle is larger. Heat evolved by reduction is eflective to vaporize water which is blown off as steam from valve J. The reaction temperature is thus maintained at a very constant value owing to cooling produced by vaporization of water under constant pressure, and also to the high blast from Ian 1'.

As operation proceeds, the proportion of hydrogen admitted into the cycle is gradually increased by causing nitrogen to be expelled little by little through blow-oi! cock N. Hence rapid reductionoi copper oxide is eflected without any risk of rush. Metal is not subjected to any overheating so that its catalytic potency is exceptionally high.

For hydrogenating an organic compound, it is vaporized by indirect heating in vaporizer E (which is of any type) through which a hydrogen stream is passed. The vapours are carried along with a large excess of hydrogen onto the catalyst so that hydrogenation can be complete, the liquid collected at G being the. required hydrogenated product directly obtained in pure condition. Nonreacted hydrogen and vapours egressing out oi catalysis tubes A, A1, A: etc, pass into condenser D; condensed liquid is collected in vessel G and hydrogen saturated with vapours is again taken up by fan! and so on.

As previously explained, reaction temperature After any stopping of the apparatus, suillce it to heat for some time with live steam to start reaction again. Upon reaction being initiated, evolved heat is sufllcient automatically to maintain temperature at proper value as previously explained, with production of vapour which for instance is forwarded to a container for any desired use.

It is still within the ambit of my invention to employ copper catalysts to which are admixed promoting agents or inert or semi-active substances, or else to bring about alterations in the apparatus above described.

In those cases in which hydrogenation should be performed at a temperature lower than C., it is only necesasry to maintain a suitable subatmospheric pressure in the inter-tube space.

Catalysts produced and used in accordance with my invention are characterized by an extraordinary activity or potency and a very long life which may be a plurality of thousand hours.

As specific examples of organic compounds capable of being hydrogenated by means of copper catalysts in accordance with this invention, I may mention saturated and unsaturated aliphatic aldehydes and ketones and, generally speaking, all compounds having an ethylenic group, saturated and unsaturated aromatic aldehydes, turfurol and derivatives thereof, alcohols liable to be converted into hydrocarbons, nitrltes and soon, it being understood that the foregoing list should not be construed in a limitative sense.

The following examples given solely for the sake of illustration will show the large potency of copper catalysts produced in accordance with this invention.

Example 1.Hydrogenating acetone into isopropanel In an apparatus as above described'and shown, comprising 40 tubes having a length of 2,500 mm. and a diameter of '76 mm., 350 litresoi lozenges or tablets of a catalyst constituted by copper oxide precipitated on pumice were placed. After starting by injecting live steam as above described, reduction was performed at a temperature of C. by maintaining a pressure of about 4 kg. per sq. cm. in the inter-tube space. Upon reduction being completed, the oven was supplied with 120 litres of acetone per hour, an excess of'hydrogen corresponding to 20 times the theoretical amount being admitted into said oven by proper adjustment of valved by-pass' P bringing the input and output sides of fan F. Temperature was maintained at C.

Under the aforesaid conditions, acetone was integrally converted and isopropanol was directly obtained from vessel G located after the condenser.

Ii supply speed: was doubled, i. e. brought to 240 litres per hour, thedistillate contained 87 per cent of isopropanol. Non-converted acetone could be separated therefrom by simple distillation. 1

Example 2.Hudrogenating crotonaldehude into butanol I used a catalyst constituted by copper oxide on kieselguhr. Reduction was carried out at 135 C. as in Example 1 and the oven was supplied with 90 litres of crotonaldehyde per hour, the catalyst being maintained at C. Conversion into butanol was practically integral and the condensate contained but 5 to 20 grams of butyraldehyde per litre.

Example 3.Hydrogenating a ethyl e propylacroleine Example 4.-Hydrogenating furjarol Pure copper obtained by reducing oxide thereof at 140 C. was used as a catalyst. By effecting hydrogenation at a temperature of 170 C. in the same oven as in the foregoing examples, supplying it with 90 litres of furfurol per hour, conversionwas complete and no further furfurol was found in the condensate; the latter consisted of 40 per cent of methylfurane and 60 per cent of furfuryl alcohol. At a lower temperature, for instance 140 (2., no methylfurane was produced and furfuryl alcohol alone was obtained.

Finally, when furfuryl alcohol instead of furfurol was passed on the catalyst, its thorough conversion into methylfurane was performed at 170 C. i

In all those reactions, no substantial production of resins or by-products was observed owing to the fact that the large amount of heat evolved- Example 5.Hz/droge nating acetaldehyde This hydrogenation could be eflected at 65 C. Consequently, after effecting reduction of copper vapours of a hydrogenatable organic substance in admixture with hydrogen through the freshly reduced copper in said elongated zone: the steps of first establishing a flow of an inert gas through said zone, heating said heat exchange liquid to copper oxide reduction temperature while simultaneously maintaining it under such a pressure as to cause said liquid to boil at said temperature, then cutting oil heating while maintaining said pressure, and gradually and slowly substituting hydrogen for said inert gas to start and maintain the copper oxide reduction rapidly but evenly and without local overheating until the reduction to copper is completed, then employing the freshly reduced copper in the catalytic hydrogenation of an organic substance by admixing vapours of said hydrogenatable organic substance with'said hydrogen at a point upstream with respect to said elongated reaction oxide at 135140 C. as above explained, the interhydrogen through an elongated reaction zone containing a charge of copper oxide and disposed zone, and continuing the flow of the mixture of gases while simultaneously bringing said heat exchange liquid under such a pressure as to cause said liquid to boil at hydrogenation temperature for said organic substance.

2. The process of claim 1, the inert gas being 4 nitrogen and the heat exchange liquid being water.

HENRI MARTIN GUINOT.

nnr'nnnncas crrnn The following references are of record in the tile of this patent! UNITED STATES PATENTS Backhaus Jan. 3, 1922 Beiararno Dec. 6, 1938 Lenth et al. May 21, 1940 Herbert Dec. 3, 1940 Nord Sept. 21, 1943 FOREIGN PATENTS country Dat Number e France June 29, 1928 Ramage Feb. 15, 1910 

